Caloric restriction (CR: reducing caloric intake 30-40 percent below ad libitum levels) remains the only intervention that reproducibly extends lifespan, reduces the incidence and delays the onset of age-related disease, enhances stress protection, and attenuates functional decline in mammals. The NIA longitudinal study of CR and aging in rhesus monkeys finished its 23rd year. Monkeys continue to be monitored regularly. Monkeys continue on a regular rotation to receive eye exams and fundus photographs. Females had a higher prevalence and severity of drusenoid maculopathy than males;this gender difference is not consistently found in humans. To date, no effect of CR has been identified but there is some indication of a genetic determinant. A major research focus for the aging monkeys continues to be behavior changes. Locomotor testing is evaluated every three years and preliminary results indicate that CR monkeys tend to be more active than controls during the day but less active at night. Complex tasks of learning and memory using custom-made portable touch-screen panels are currently underway. Motor performance was assessed using an automated monkey Movement Assessment Panel (mMAP) that has reproducibly and reliably measured reaction time, coarse-motor, and fine-motor movement in rhesus monkeys and humans. In our study, an age-related decline in fine motor performance has been observed that was partially ameliorated in the CR monkeys, this difference has persisted during 6 years of testing. We continue to monitor morbidity and mortality.